





OLD CROW 







211 









Iridoprocne bicolor (Vieillot) 













Male 







Female 







Weight 



Fat 



Testes 



Weight 

 (.0.) 



Fat 



Eggs 



Date 





(mm.) 







May 16 



20.8 



F 



7x10, 7x9 



21.8 



F 



1 



May 20 



22.9 



F 



7x9.6, 8x10.5 



24.2 



F 



1 



May 22 



22.7 



F 



7x10, 8.6x11 









May 24 









21.4 



F 



1 



(aver.) 



22.1 







19.8 

 21.8 



F 



1 



The first tree swallow was seen at about 2 : 30 p.m. on May 16, and 

 within a few hours a number of them were inspecting the bird houses 

 about the village. The numbers increased until on May 23 about 30 

 were circling in an area about a quarter mile long over the river bank. 

 A little later the group comprised about 40 which were coursing in 

 circuits about 300 yards in length over the meadow retrieving insects 

 from among the flooded grasses. At this date they were still flying 

 actively at 8 : 30 p.m. Toward the end of May the number of tree 

 swallows about the village diminished as every nest box became oc- 

 cupied by a pair. Some must have migrated further or dispersed 

 to natural nesting sites. Along the river tree swallows were occasion- 

 ally seen but their natural nesting places were not discovered. 



The number of tree swallows, which the Indians call Sha sove, was 

 much exceeded by the cliff and even more numerous bank swallows. 



It was noticed that some tree swallows with scarcely a trace of blue 

 on their slate-gray backs were mating as females and occupying nest 

 boxes. Two gray females taken for examination were indistinguish- 

 able in appearance of maturity from blue females. 



Tree swallows are not reported from the Mackenzie Delta (Porsild, 

 1943) but extend across the wooded portion of arctic Yukon and 

 Alaska. Their arrival was surprisingly early for an insectivorous 

 swallow, preceding the breakup of river ice by six days, but all speci- 

 mens were fat. In view of their early commonness in British Colum- 

 bia (Munro and Cowan, 1947) and arrival April 10 at Craig, Alaska, 

 it is likely that the migration passes to the northwest through many 

 western valleys and is likely over a western fly way. 



Riparia riparia riparia (Linnaeus) 



On May 31 a few bank swallows were noticed, and by June 1 they 

 were as numerous about the village as tree swallows, whose feeding 

 areas they shared. Their number then increased until it exceeded by 

 many times that of the other swallows. 



In groups of various sizes bank swallows nested in selected situ- 

 ations along the river. Their numbers are tremendous, but the greatest 

 concentration was noticed in the vicinity of the village. 



